{
const ctx = DOM.context2d();
ctx.canvas.width = width;
ctx.canvas.height = height;
ctx.fillStyle = 'lightskyblue';
ctx.beginPath();
line.context(ctx)(points3);
ctx.lineTo(width, height);
ctx.lineTo(0, height);
ctx.closePath();
ctx.fill();
ctx.fillStyle = '#999';
points3.forEach(point => {
ctx.beginPath();
ctx.arc(point[0], point[1], 5, 0, 2 * Math.PI);
ctx.fill();
});
return ctx.canvas;
}